Thread-rolling tool



G R E B L L A H W A THREAD-ROLLING Toorl 2 sheds-sheet 1 Filed July 29, 1942 may 39 WMO A. W. HALLBRG THREAD-ROLLING TOOL Filed July 29 1.942 2 Sheets-Sheet 2 Patented May 30, 1944 THREAD-ROLLING TOOL August W. Hallberg. Waterbury, Conn., assignmto Chase Brass a Copper Co. Incorporated, Waterbury, Conn., a corporation Application July 29, 1942, Serial No. 452,722

2 Claims.

This invention relates to improvements in thread-rolling tools.

One object of this invention is to provide an improved thread-rolling tool for rolling threads on the interior of a tube-end such as the end of a tube or pipe or of a tubular iltting for tubes or pipes.

Anothenobject of this invention is to provide an improved thread-rolling tool for rolling threads on the interior of a tube-end, and formed of simple elements readily manufactured and readily assembled to produce an efficient construction.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art.

In the accompanying drawingsl forming part of the present disclosure, in which one way of carrying out the invention is shown for illustrative purposes:

Fig. 1 is a front elevational view illustrating one embodiment of the invention;

Fig. 2 is a longitudinal sectional view on line 2-2 of Fig. 1, showing the thread-rolling tool and a portion of a tube that is being threaded by the tool;

Fig. 3 is a sectional view on line 3-3 of Fig. 2;

Fig. 4 is a sectional view on line 4-4 of Fig. 2;

Fig. 5 is a, right-end elevation of the front end of the thread-rolling tool;

Fig. 6 is a top plan view of the front-end portion of the thread-rolling tool;

Fig. 7 is a fragmental sectional view on line 1--1 of Fig. 5;

Fig. 8 is an elevational view of one of the thread-rolling members;

Fig. 9 is a sectional view of an expanded tubeend before threading;

Fig. 10 is a sectional view of the tube-end of Fig. 9 after having been threaded; and

Fig. 11 is a sectional view of a. T-iitting which has been threaded.

In the description and claims, the various parts and steps are identified by specific terms for convenience, but they are intended to be as generic in their application as the prior art will permit.

The particular thread-rolling tool chosen for illustrating vthe present invention includes a shank preferably having three shaft-receiving holes 2| into which shafts or arbors 22 can be inserted through the front end-face 23 of the shank.. Each arbor 22 is adapted to receive a thread-rolling roll 25 rotatably mounted thereon, the shaft 22 extending across the socket 24 and being supported by the front wall 26 and rear wall 21 adjacent the socket 24 with the threadrolling roll 25 mainly housed in the socket 24. The rear end of each shaft-receiving hole 2l opens into a milled slot 28 so that holding-screws 29 threadedly carried in a ring 30 can be screwed down to clamp the inner ends of the arbors 22 to hold them in place, and to facilitate engaging a tool against the inner ends of the arbors 22 when it'is desired to disassemble them.

For convenience, the front or` forward endportion 3l of the shank 2l), whose outside diameter is substantially smaller than the inside diameter of the tubular part to be threaded, may be conveniently referred to as the shank-end, and the tube-end portion 32 which is to be threaded and which may form the end-portion of an actual tube 33 such as illustrated in Figs. 9 and 10, or the terminal-portions of a tube-tting or pipe-fitting such, for example, as the T 34 shown in Fig. 11, may for convenience be referred to as a tube-end.

Tube-ends may be internally threaded in accordance with the present invention by many different embodiments of tools. Thus, in Fig. l, the chuck-jaws 35 carried by the rotatable headstock of a lathe are shown as clamping the tool or shank 20 for rotation to roll threads on the interior of the tube-end 32, which in the particular embodiment shown, is shown as clamped by a clamping-device 36 carried by the toolslide of a lathe which is fed toward the threadrolling tool by means of the lead-screw 31 at the proper rate, in order to roll the proper desired thread upon the interior surface of the tube-end 32. Not only can the particular mechanism for carrying out the threading operation on the tube-end to be threaded be of many forms, but also instead of rotating the tool while the tube-end is stationary, the tube-end could be rotated While the tool is held stationary, as will be understood by those skilled in the art.

Each thread-rolling roll 25 has its threadrolling surface formed by a plurality of threadrolling ribs 38 of the same `outside diameter, and one smaller-diametered thread-rolling rib 39 which starts or initiates the thread-rolling operation upon the inner surface of the tube-end, the formation of a thread upon the tube being accomplished by the annular V-shaped ribs 38 and 39 by virtue of the thread-rolling elements having their axes arranged somewhat askew, as is shown in Fig. 7, so as to have the inclination of the thread-rolling ribs correspond to the inclination of the thread to be rolled.

It will -be noted that in rolling f the threads upon the inside oi' the tube-end, the diameter across the threads becomes substantially smaller than the inside diameter of the tube-portion before the rolling operation, owing to the fact that no metal is cut off but the metal is forced to ilow more or less radially inward in forming the screw-threads. Thus, it will be seen that this mode of forming screw-threads is especially applicable to thin-walled tubes such, for example, as copper or copper-base-alloy tubes, which can be comparatively thin. By merely rotating the thread-rollng member, or the tubular member being threaded, in the reverse or unthreading direction, the threading-tool can be readily Withdrawn from the tube-end being threaded.

The invention may be carried out in other speciiic ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore. to be considered in all respects as illustrative and not restrictive, and

all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

l. A thread-rolling tool for rolling threads on the interior of a tube-end, comprising: a shank having a shank-end of substantially smaller outside diameter than the inside diameter oi said tube-end; said shank-end having a plurality of sockets a substantial distance back from the front face of the shank-end to provide a front wall and a rear wall at opposite sides of each socket, said sockets opening through the perimetric surface of the shank-end; a shaft for each of said sockets, each shaft being supported -by said front and rear walls and extending across a socket and. being insertable and removable through the front face of said shank-end: a locking-ring surrounding said shank and having locking-means releasably iockingly-engaging the rear ends of said shafts; and a thread-rolling member for each socket, each thread-rolling member being supported by a said shaft for rotation in a socket and projecting beyond said perimetric surface; said thread-rolling members being adapted to roll a thread on the interior of said tube-end Awhen saii shank-end is moved helically into said tubeen 2. A thread-ro1ling tool for rolling threads on the interior of a tube-end, comprising: .a shank having a shank-end of substantially smaller outside diameter than the inside diameter of said tube-end; said shank-end having a plurality of circumferentially-separated sockets a substantial distance back from the front face of the shankend to provide a. front wall and a rear Wall at opposite sides of each socket, said sockets opening through the perimetric surface of the shankend; a shaft for each of said sockets, each shaft being supported by said front and rear walls and extending across a socket and being insertable and removable through the front face of said shank-end and releasably lockable in its inserted position; and a thread-rolling member for each socket, each thread-rolling member being supported by a said shaft for rotation in a socket and mainly located within but having a minor portion projecting beyond said perimetric surface; said thread-rolling members being adapted to roll a thread on the interior of said tube-end moved helically into saidwhen said shank-end is tube-end.

AUGUST W. HAHBERG. 

